Asked by Ceridwen George, Essex

Carbon-wise, it's one of the greenest ways to travel, but cruising along a river can cause pollution and disturb wildlife. There are two key laws that apply universally: it is illegal to discharge toilet waste and flush more than 5mg per litre of oil or fuel into the water.

The Royal Yachting Association and British Marine Federation provide a list of places in the UK that provide "pump out" facilities where you can dispose of toilet waste along the river or canal (thegreenblue.org.uk).

It's also far greener to go on an electric boat rather than one that uses a diesel engine; they are cheaper to run (most marinas now have charging facilities), their stealth makes it easier to get closer to wildlife, and their low wash won't disturb bird nests on the river banks. The website of the Electric Boat Association (electric-boat-association.org.uk) provides a list of companies that run electric river cruises, such as Avon Boating in Stratford (avon-boating.co.uk), and the Phoenix Fleet on the Norfolk Broads (phoenixfleet.com). Better still to go on a solar-powered boat, such as the 46ft Solar Heritage catamaran in Chichester harbour (conservancy.co.uk) and two 40ft launches on Lake Coniston in the Lake District (conferry.co.uk).

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